Self-aligned cuts are critical for smaller technology nodes, e.g., 7 nm nodes and beyond, to mitigate edge placement error (EPE). Self-aligned cuts can be achieved through pillar technology or trench lithography and tone inversion approaches with careful multiple materials selection with high etch selectivity.
As dimensions shrink beyond 7 nm nodes, e.g., <40 nm pitch, the trench and tone inversion approach becomes the preferred path due to narrower lithographic printability margin/flop, compared to the conventional pillar approach. However, the trench and tone inversion approach creates additional steps and complexities that require, e.g., good gap fill, planarization material. In addition, the trench and tone inversion approach for smaller technologies requires new materials that can have superior etch selectivity. However, using new materials would create additional issues. These issues range from the need for new etch back or CMP processes to the optimization of the RIE processes, each of which would have a prolonged learning cycle when introduced into the fabrication environment.